To discover what the Stoics precisely mean by eudaimonia, surveying how the concept belongs within a greater tradition that spans a diverse collection of philosophers and schools is illuminating. Arthur Long provides a useful account of this shared conception of human flourishing, which serves as helpful background for identifying what is individually interesting about the Stoic position. Happiness, within this tradition, is conceptualized as a manifold. It is what all humans desire, identified with the acquisition of the good, a possession of the divine, profitable, involves freedom, living well, and lastly, an ultimate end sought in and for itself (Long 81). Furthermore, happiness is a state and activity of our soul, with ethical virtue being the relevant active state in the case of flourishing. Though, this marks the first departure from tradition made by the Stoics.
	While most ancient conceptions argued for a plurality of powers or souls, often including a non-rational sort among their number, the Stoics offered a singular account. The Stoic soul is rational through-and-through. Consequently, the Stoics took virtue to be the only good. As Diogenes Laertius relates, the Stoics viewed the clear sign of the good as that which is beneficial, and what is bad, the opposite. Further, as those fickle things --health, wealth, status, etc. -- tend to swing between harm or help, it then follows for the Stoics that steadfast virtue is the only good ( Long & Sedley 345 58A). With this framework, of virtue as the sole good, vice the only evil, and all other things being indifferent (though this comes with qualifications), the Stoics furnish the radical thesis that happiness consists in living in accordance with virtue and in agreement with nature (394 63A). That said, there are as many modifications to this idea as there are Stoics, and how we should grasp this notion in its variety of formulations is a question I shall take up in the coming section.
	I will expand upon the category of indifferents. Although the bodily and external affections of this class have no direct bearing on happiness themselves (though perhaps an indirect one), they do possess a salient relationship to virtue, and as I shall now show, it raises serious practical questions that will have an impact on the attractiveness and coherency of Stoic ethics. To qualify indifferents, the Stoics took there to be three sorts of evaluations that we can make. They can be preferable (health), dispreferable (illness), or absolutely indifferent (contracting a finger). The first and second varieties can compel or repulse us, respectively, while the latter type does not excite any choice or avoidance whatsoever (354 58B). Though, the orthodox Stoics tread carefully with this distinction, as they wish to avoid the conclusion of Aristo of Chios, who argued that all things between the poles of virtue and vice are absolutely indifferent. On the one hand, Aristo believes that calling something preferable implies, in some sense, that the thing is good, which is unacceptable in the Stoic schema. On the other hand, in certain situations things preferred by nature, e.g. health, may turn out to be dispreferable, if being able-bodied means we will be drafted by a tyrant and surely die in battle (354-5 58F). As Aristo views it, between indifferents there is no natural priority, but rather preferences dictated by circumstance. However, if this conclusion is accepted, the grounds on which I may wisely select things, whether I should use the bike with well-inflated or flat tires, for instance, recedes from sight. Orthodox Stoics sought to avoid both these conclusions and to preserve the claim that virtue is the only good while still providing a method of selection. It could be conceded that there are special situations where it is sensible to call what is normally valuable the opposite, though this does not prove that being healthy is not a natural preference. Just that, if a tyrant is drafting people, it may not be so bad to have a stomach ache. The sketch so far should make a few features of the Stoic position clear: virtue alone is sufficient for us to be happy and though indifferents do not directly contribute to happiness, they do play a role in making the ethical engine run. Though at this point I have yet to provide a substantial sense for happiness, and this is what I shall do now.